1. Field of the Invention
The present invention relates to a surface treatment process for enhancing the release rate of metal ions from a sacrificial electrode, and more particularly, to a surface treatment process for enhancing the release rate of iron ions from an iron electrode. The sacrificial electrode is commonly used as an anode in electroplating and for electro-coagulation devices.
2. Description of the Related Art
Electrodes are the most important elements in electrochemical reactions, and their reactivity is of critical importance for process reaction rates. With regards to many related prior art technologies, most emphasize how to avoid corrosion of the electrode to extend the electrode's lifetime and its measurement accuracy. However, for a sacrificial electrode (as is used, for example, in an electro-coagulation device, which employs the sacrificial electrode to generate iron and aluminum irons for forming iron hydroxide and aluminum flocculation in a water processing device for), the primary concerns involve preventing the electrode from generating a passive film, improving the electrode corrosion rate, and uniformity of etching. The sacrificial electrode corrosion rate determines a release rate of metal ions and the reactivity of the sacrificial electrode. When a passive film is generated on the electrode, the reactivity of the electrode is reduced, which leads to excessive power consumption. Moreover, uneven corrosion generates pits and cracks in the electrode, reducing the electrode's lifetime.
The generation of such passive films is the primary reason for electrode inactivity. The passive layer is an insoluble oxide layer or organic layer that adheres to the surface of the electrode. The passive layer is very easily formed, and may have many different compositions.
Taking an iron electrode as an example, when the iron electrode is placed in a water solution, a FeOOH passive layer forms on the iron electrode, which has very low solubility, and so the iron ion release rate of the iron sacrificial electrode is reduced. As another example, consider the electro-coagulation process for waste water of a semiconductor chemical mechanical polishing process, which utilizes many different components for the polishing formula. Some of these chemical components may cause the electrode to generate a passive layer. Consequently, how to remove the passive layer, or prevent the formation of such a passive layer, is very important.
Most of the prior art electrode surface treatment processes focus only on how to prevent the corrosion of the electrode.
Therefore, it is desirable to provide a surface treatment process for enhancing the release rate of metal ions from a sacrificial electrode to mitigate and/or obviate the aforementioned problems.